As the U.S. presidential race gets underway, Hollywood's biggest stars have started stumping for their favorite candidates. Oprah Winfrey has already appeared at rallies for Barack Obama this weekend, saying that "Barack will bring statesmanship to the White House." Will Smith is also supporting the Democratic junior senator. "Barack represents what I feel is the future of the optimum survival of America." Meanwhile, Kevin Bacon and Tim Robbins will be joining Democrat John Edwards on the campaign trail in Iowa this week. As for Hillary Clinton? She's got the star power of her hubby, former President Bill Clinton!